Certified Wound Ostomy Nurse (CWON) Practice Test

Which antimicrobial dressing is toxic to bacteria and fungi but not to good cells?

1. Cadexomer iodine

2. Sustained release silver dressings

3. Manuka honey-based dressings

4. Methylene blue dressings

The correct answer is: Sustained release silver dressings

Sustained release silver dressings are considered effective for their antimicrobial properties while being less harmful to healthy cells. Silver ions released from these dressings demonstrate a broad-spectrum antimicrobial activity against bacteria and fungi. They work by disrupting bacterial cell walls and interfering with microbial DNA replication, which ultimately leads to cell death in pathogens. Importantly, these dressings are designed to minimize toxicity to surrounding healthy tissue. In contrast, other options, like cadexomer iodine and methylene blue dressings, may have a broader spectrum of activity that can also affect healthy cells. Cadexomer iodine, while effective at reducing microbial load, can sometimes be cytotoxic, impacting cellular viability. Methylene blue has some cytotoxic effects as well, especially in higher concentrations, which may affect normal cellular function. Manuka honey-based dressings possess natural antimicrobial properties primarily due to the presence of hydrogen peroxide and other compounds, but they do not have the sustained release mechanism like silver dressings, which allows for prolonged antibacterial action while being gentle on healthy cells.